A Myanmar court has handed three-year sentences to former leader Aung San Suu Kyi and Australian economist Sean Turnell for violating Myanmar’s official secrets act, a legal official says.

The pair were tried and convicted under the secrets law, said the official, who spoke on condition of anonymity because he is not authorised to release information about the case.

Three members of Suu Kyi’s former Cabinet were also found guilty, each also receiving sentences of three years.

Turnell, an associate professor in economics at Sydney’s Macquarie University, had served as an adviser to Suu Kyi, who was detained in the capital Naypyitaw when her elected government was ousted by the army on February 1, 2021.

He has been in detention for almost 20 months. He was arrested five days after the military takeover by security forces at a hotel in Yangon, the country’s biggest city, while waiting for a car to take him to the city’s international airport.

He had arrived back in Myanmar from Australia to take up a new position as a special consultant to Suu Kyi less than a month before he was detained. As director of the Myanmar Development Institute, he already had lived in Naypyitaw for several years.

The day after the military’s takeover, he posted a message on Twitter that he was: “Safe for now but heartbroken for what all this means for the people of Myanmar. The bravest, kindest people I know. They deserve so much better.”

He was charged along with Suu Kyi and the three former Cabinet ministers on the basis of documents seized from him. The exact details of their offence have not been made public, though state television said last year that Turnell had access to “secret state financial information” and had tried to flee the country.

Turnell and Suu Kyi denied the allegations when they testified in their defence at the trial in August.

Turnell was also charged with violating immigration law, but it was not immediately clear what sentence he received for that.

Foreign Minister Penny Wong said Australia “rejects” the court ruling in Myanmar and will continue to “advocate strongly” for Turnell’s release.

“Professor Turnell was tried in a closed court. Australia’s Chargé d’Affaires and consular officials in Myanmar made every effort to attend the verdict but were denied access to the court,” Wong said.

“The Australian Government has consistently rejected the charges against Professor Turnell during the more than 19 months he had been unjustly detained by the Myanmar military regime.”

Amnesty International Australia Impact director Tim O’Connor said Turnell was denied a fair trial or adequate access to legal counsel.

“The proceedings have been an outright sham and Mynamar’s military must immediately release Turnell so he can return to his family,” he said.

“Today’s conviction is the latest in a string of politically motivated cases all designed to cement the rule of the rights-abusing Myanmar military.”

Tweet from @HumanRightsUNSW

Myanmar’s colonial-era official secrets act criminalises the possession, collection, recording, publishing, or sharing of state information that is “directly or indirectly, useful to an enemy.”

The charge carries a maximum penalty of 14 years in prison.

All sessions of the trial, held in a purpose-built courtroom in Naypyitaw’s main prison, were closed to the media and the public. The defence lawyers were barred by a gag order from revealing details of the proceedings.

The same restrictions have applied to all of Suu Kyi’s trials.

The case that concluded on Thursday is one of several faced by Suu Kyi and is widely seen as an effort to discredit her to prevent her return to politics.

She had already been sentenced to 20 years’ imprisonment after being convicted of illegally importing and possessing walkie-talkies, violating coronavirus restrictions, sedition, election fraud and five corruption charges.

The cases are widely seen as being concocted to keep the 77-year-old Suu Kyi from returning to active politics.

Suu Kyi is still being tried on seven counts under the country’s anti-corruption law, with each count punishable by up to 15 years in prison and a fine.